Phosphorus sulfide-hydrocarbon products and method for preparing the same



United States Patent 3,234,203 PHOSPHORUS SULFIDE-HYDROCARBON PRODUCTS AND METHOD FOR PRE- PARIN G THE SAME William O. Henley, West Deptford Township, Gloucester County, and Ferdinand P. Otto, Woodbury, N.J., assignors to Socony Mobil Oil Company, Inc., a corporation of New York No Drawing. Filed Dec. 17, 1962, Ser. No. 244,908 12 Claims. (Cl. 260139) The invention is directed to phosphorus sulfide-hydrocarbon reaction products and to a process for preparing the same. It also contemplates the production of barium salts of such products and the use of these salts as lubricating oil additives.

The use of barium salts of phosphorus sulfide-hydrocarbon reaction products as lubricating oil additives has been known for some time. Furthermorefit has been recognized that basic salts of phosphorus sulfidehydrocarbon products, i.e., salts having higher metal contents than mere neutral. (i.e., normal) salts, are more effective engine oil-.detergents, on a weight for weight basis, than the neutral salts; Also, it is known that by increasing the metal contents of these salts their basicities are increased whereby they are more effective than lower barium-content salts in neutralizing acids formed by combustion of fuel, particularly high sulfur-content fuels commonly employed in diesel engines. The art, therefore, has sought to prepare barium salts having the highest possible barium contents (i.e., high barium to phosphorus ratios) and a number of methods of preparing such salts have been proposed heretofore. A highly advantageous method of this type is disclosed in a copending application, Serial No. 173,340, filed February 15, 1962, by Emil Koft, Jr., and Ferdinand P. Otto, one of the present applicants. In some of these prior art processes, the

phosphorus sulfide-hydrocarbon reaction products are subjected to various treatments, e.g., hydrolysis, prior to the formation of the barium salts. These treatments may frequently bring about formation of byproducts which must be removed in order to avoid the formation of oil-insoluble barium salts. These treatments may also cause significant loss of sulfur in the phosphosulfurized products which is also undesirable, since it lessens the antioxidant properties of the salts prepared therefrom.

' It is an object of the present invention to provide an improvement in the known methods for preparing this commercially valuable class of barium salts of phosphorus sulfide-hydrocarbon reaction products. It is also an object to prepare salts having high S:P ratios and to avoid loss of sulfur in such preparation. It is another object to prepare such high sulfur salts having improved antioxidant properties. It is a further object to provide a novel method for the preparation of an intermediate useful for making such salts. It is a still further object to carry out such methods so as to avoid formation of lubricating oil-insoluble by-products in the phosphosulfurized-hydrocarbon salts which are otherwise completely soluble in lubricating oil. These and further objects will become apparent from the following detailed description of the invention, in which parts and percentages, where stated, are by weight.

Broadly, the process of this invention comprises subjecting a phosphosulfurized hydrocarbon to the action of air or oxygen for a relatively short period of time at a moderately elevated temperature. The air-treatment does not bring about any appreciable weight-loss, nor does it materially alter the P28 ratio. This air-treated intermediate is especially useful without hydrolysis for 3,234,203 Patented Feb. 8, 1966 the production of barium salts having high Ba:P ratios. These salts are completely soluble in lubricating oil to form clear'solutions therewith. They are also effective oil antioxidants.

The process of the invention may be applied to phosphorus sulfide-hydrocarbon reaction products in general. Thus, the phosphorus sulfides used to prepare these products may be any of the known phosphorus sulfides, such as P 8 P 8 P 5 etc., P 8 being most commonly used.

The hydrocarbons which may be phosphosulfurized, for example, may be any of these described in detail in US. Patents Nos. 2,316,080, 2,316,082 and 2,316,088, issued April 3, 1943, to Clarence M. Loane and James W. Gaynor, and U8. Patent No. 2,806,022, issued September 10, 1957, to Albert R. Sabol.

Briefly, the hydrocarbon constituent is usually a monoolefinic hydrocarbon polymer resulting from the polymerization of low molecular weight mono-olefinic hydrocarbons, such as propylenes, butylenes and amylenes, or copolymers obtained by the polymerization of hydrocarbon mixtures containing iso-mono-olefins and monoolefins of less than 6 carbon atoms. The polymers may be obtained, as is Well known in the art, e.g., by polymerization of these olefins or mixtures of olefins in the presence of a catalyst, such as sulfuric acid, phosphoric acid, boron fluoride, aluminum chloride or other similar halide catalysts of the Friedel-Crafts type, Ziegler type catalysts, etc. I

As shown in the art, the phosphorus sulfide-hydrocarb on reaction product may be prepared by reacting the hydrocarbon with from about 1% to about 50%, and preferably from about 5% to about 25%, of a phosphorus sulfide, e.g., P 8 at a temperature of from about C. to about 350 C, in a non-oxidizing atmosphere, such as an atmosphere of nitrogen. The reaction is carried out for from about one to about 10 hours or more and preferably for at least about 5 hours. Phosphosulfurized hydrocarbons formed by the reaction of phosphorus pentasulfide with olefin polymers having molecular weights of from about 500 to about 50,000, particularly polypropylenes and polybutylenes having molecular weights of from about 500 to about 1500, are frequently preferred for making the barium salts.

In essence, the present invention provides for the production of valuable intermediate products by subjecting any of the various phosphosulfurized hydrocarbons to air-treatment at a temperature of from about C. to about 200 C. and preferably at a temperature of about C. by suitable means, such as by introducing air into the stirred reaction mass. The time of air treatment may vary widely depending on temperature and rate of air feed, generally about 1 to S hours is effective so long as the hydrocarbon is not substantially oxidized. The rate of introducing the air may be varied widely depending somewhat on the size of equipmentused. For most effective operation, the air is introduced into the reaction mass at a rate of about 0.115 to 2.00, preferably from about 0.2 to 0.5, liters per minute per kilogram of phosphosulfurized hydrocarbon being treated. Higher amounts of air may be used if desired, particularly at the higher temperatures of the preferred ranges. Faster rates and higher temperatures are sometimes used to produce the desired products more quickly but care should always be exercised to avoid undue oxidation as indicated by a major change in the P28 ratio. The air-treated product may be used as such or may be filtered through an adsorbent material, such as Attapulgous clay, fullers earth, diatomaceous earth or the like, at a temperature of from about 50 C. to about 200 C. to obtain a filtrate substantially Q2 free of inorganic phosphorus acids, low molecular weight organic phosphorus compounds or other undesirable by-products. It has been found that the air-treatment provides better barium utilization and improved overall processing in producing the barium salts from the treated phosphosulfurized hydrocarbon. In addition, the air-treatment brings about these improvements Without any substantial loss of sulfur with its attendant anti-oxidant property. This air-treated reaction product, after filtration, may be converted to the barium salt by any of the suitable prior art processes. Usually the product is diluted in a nromally liquid hydrocarbon, generally the same or similar to the hydrocarbon in which the finished additive-is to be employed, to a phosphorus content of from about 0.01% to about and preferably to a level of from about 1% to about 2%.

A fuller understanding of the invention will be had from the following illustrative examples.

EXAMPLE 1 (a) 226.1 grams of phosphorus pentasulfide were added over a period of 40 minutes to 1506 grams of polypropylene (molecular weight=688, K.V. at 8210 F..=24.6 es.) in a nitrogen atmosphere at 185-225 C. in a suitable reaction vessel. This reaction mixture was then heated and stirred under a nitrogen atmosphere for hours at 220- 225 C. The product was filtered through an-electrically heated, Hyflo-precoated Biichner funnel at 120 C. The phosphosulfurized polypropylene filtrate gave an analysis of P, 3.74% and S, 5.50%. (Hyflo is a commercial grade of diatomaceous earth filter aid.)

(b) 1386 grams of this phosphosulfurized polypropylene (P, 3.74% and S, 5.50%) were charged to a reaction chamber provided with a stirrer, thermometer, gas introduction tube and a gooseneck gas vent. Air was passed into the charge, while the material was stirred, at 150 C. for 3 hours at a rate of 0.30.4 liter/minute. The airtreated product so prepared gave an analysis of P, 3.67% and S, 5.46%.

EXAMPLE 2 The following reaction was carried out in a suitable vessel fitted with a mechanical stirrer, thermometer, dropping funnel and a condenser arranged for take-ofi of condensate. This is one of the well-known methods for making a barium salt of a phosphosulfurized hydrocarbon. The initial charge to the vessel was 75 parts of the nonair treated, phosphosulfurized polypropylene (P, 3.74% and S, 5.50%) as prepared in Example 1(a) and 103 parts of process oil (a conventional, 100 sec. at 110 F., paraffin oil). Seventy parts of barium methylene reagent (12.1% barium) were slowly added to the oil blend at 90100 C. as methanol was continuously removed by distillation. The reaction mixture was then cooled and mixed with a solution of 70 parts of the 12.1% barium methylate reagent and 4.5 parts of H 0, and the resultant mixture was refluxed for three hours at 69 C. Methyl alcohol and water solvent were removed by distillation and solvent removal was completed by sweeping the reaction mixture with nitrogen at 150 C. for one hour. The product was carbonated for one hour at 150 C. and then cooled to 120 C. Hyfio-filter aid (5% by weight) was added and the product filtered through an electrically heated Hyfio-pretreated Biichner funnel. The filtrate was so cloudy upon filtration that no attempt was made to add more barium to it. The product was too insoluble in the oil to be commercially useful.

EXAMPLE 3 The following reaction was carried out (as in Example 2) in a suitable vessel fitted with a mechanical stirrer, thermometer, dropping funnel and a condenser arranged for take-off of condensate. The initial charge to the flask was 75 parts of the air-treated, phosphosulfurized polypropylene (P, 3.67% and S, 5.46%), final product of Example 1(b), and 100 parts of process oil (100 sec. at

110 F. parafiin oil). Sixty-five parts of barium methylate reagent (12.7% barium) were slowly added to the oil blend at -90 C. as methanol was continuously removed by distillation. The reaction mixture was then cooled and mixed with a solution of 65 parts of barium methylate reagent (12.7% barium) and 3.3 parts of H 0 and the resultant mixture refluxed for three hours at 69 C. The methyl alcohol and water solvent were removed by distillation and solvent removal completed by sweep ing the reaction mixture with nitrogen at 150 C. for one hour. The product was next carbonated at 150 C. for one hour. After carbonation the product was clear and, on cooling to room-temperature, theproduct was mixed with a methyl alcohol solution of 65 parts of barium methylate reagent (12.7% barium) and 3.2 parts of distilled water and the mixture refluxedfor three hours at 69 C. The alcohol solvent was removed by distillation and solvent removal completed by sweeping the reaction mixture with nitrogen at 150 C. for one hour. The product was then carbonated for one hour at 150 C., cooled to 120 C., 5%, by Weight, of Hyfio-filter aid added and filteredthrough an electrically heated Hyfloprecoated Biichner funnel to yield a clear filtrate and a completely oil-soluble barium salt of the air-treated phosphosulfurized polypropylene.

Analysis of salt Barium, percent 12.1 Sulfur, percent 1.89 Phosphorus, percent 1.38 CO (combined), percent 2.5

Even though the methods used for preparing the barium salts in Examples 2 and 3 were essentiallythe same, it is clearly evident from the results obtained in Example 3 that the air-treated product of Example 1(b) gives oilsoluble barium salts which form clear solutions. However, the use of the samev phosphosulfurized hydrocarbon of Example 1(a), without the air-treatment, as shown in Example 2, gives cloudy suspensions of oil-insoluble products which were not cleared up by the same filtration procedures used in Example 3.

EXAMPLE 4 The processes of Examples 1 and 3 were duplicated in all respects, to produce two additional quantities of barium salts of air-treated P S -polypropylene products. These salts were substantially the same as produced in Example 3 and were identified as Examples 4A and 4B, respectively. The analyses of these samples appear in Table I below.

The process of Example 1(a) was twice repeated to produce filtered P S -polypropylene reaction products substantially the same as those describe-d inExample 1 (a) These reaction products, instead of being air-treated, were then hydrolyzed ,at 150160 C. by introducing steam into the reaction masses for six hours. 75 parts of each of the hydrolyzed products were diluted with parts of process oil (100 sec. at F. parafiin oil) and the solutions were separately dried at 160 C. with a nitrogen purge. Each of the dried products was then converted into a barium salt by following the same procedure set forth in Example 3, except that the hydrolyzed products were used in place of the air-treated products shown in Example 3. The barium salts so produced were designated, respectively, as Samples 4C and 4D. The analyses of these samples appear in Table I. The phosphosulfurized polypropylene used to prepare salt 4C contained 3.87% P and 5.40% S before hydrolysis and 2.68% P and 1.65% S after hydrolysis. The phosphosulfurized polypropylene used to prepare salt 4D contained 3.97% P and 6.59% S before hydrolysis and 4.05% P and 3.17% 3 after hydrolysis.

The oxidation inhibiting properties of barium salts 4A, 4B, 4-Cand 4-D were determined by subjecting the salts to the Catalytic Oxidation Test.

CATALYTIC OXIDATION TEST (C.O.I.)

This test determines the effectiveness of an additive in preventing catalytic oxidation of an oil. The test procedure is as follows. In a 200 x 25 mm. test tube is placed a 25 cc. sample of test oil having immersed therein (a) 15.6 sq. in. of sandblasted iron wire, (b) 0.78 sq. in. of polished copper wire, (0) 0.87 sq. in. of polished aluminum wire and (d) 0.167 sq. in. of polished lead surface. The oil is heated to a temperature of 260 F. and maintained at this temperature, while drying air is being passed therethrough, at a rate of 18 liters per hour, for 40 hours. The results of the test are reported in terms of stability number of the additive. The stability number 'is the percentage of additive (in the oil) multiplied by 100, that reduces the N.N. (Neutralization Number) of the reference oil to a value of 2. Thus, the lower the additive stabilitynumber, the more effective the additive and vice versa;.

The results of the C.O.T. tests are presented in Table I. The base oil used in all of the tests was an SAE 20- grade, solvent-refined, Pennsylvania oil (K.V. at 210 F. =53.83).

It is clearly evident that salts 4-A and 4B made with the air-treated products are markedly superior as oxidation inhibitors than are the similar salts 4-C and 4-D made with the hydrolyzed products. The hydrolysis step has heretofore been accepted in the art as a preferred procedure in the production of this class of barium salts.

The barium salts prepared from the air-treated phosphosulfurized hydrocarbons of this invention have been repeatedly evaluated and have been found outstandingly effective as lube oil detergents in conventional lube oil blends.

The barium salts of the air-treated phosphosulfurized hydrocarbons may be prepared by the procedure set forth in Example 3 or any of the other suitable procedures shown in the prior art for making such salts. Various methods have been described in the art for obtaining salts containing large amounts of barium and these include repetition of the several steps to gradually build up the barium content. Any of these methods may be used in the present invention since the use of the new air-treated intermediates results in superior end products. Some of the specific features of these processes are set forth in greater detail hereinafter, especially as they may apply to the successful practice of the present invention.

The employment of a hydrocarbon solvent for -the airblown phosphorus sulfide-hydrocarbon reaction products is advantageous in this process due to the fact that these reaction products, as well as the high barium-content sait products, are generally quite viscous. The solvent reduces the viscosity of the reaction mixture and greatly facilitates the process, particularly the carbonation step(s) and the final filtration and handling of the product. Any of the known hydrocarbon solvents of suitable boiling range, such as petroleum oil, petroleum naphtha or the like may be used. The use of a mineral oil, however, is preferred, since it need not be removed from the final product, the oil solution of the product thus obtained being directly blendable with a base lubricating oil desired to be improved therewith.

The barium methylate-methanol reagent utilized in this process may be prepared by reaction of barium oxide with excess methanol to provide a methanol solution of barium (as barium methylate). The ratio of methanol to barium (as barium methylate) in this reagent may suitably vary from about 20 to about 40 mols of methanol per mol of barium, the preferred ratio being from about 25 to 30 mols of methanol per mol of barium.

The presence of water along with the barium methylate reagent is necessary for the success of the process of making the barium salt. It is known that amounts of Water varying between about 2 and about 4 mols per mol of barium (as barium methylate) are suitable, the preferred amount being from about 2.5 .to about 3 mols per mol of barium.

The amount of barium (as barium methylate) charged to the initial reaction with the air-blown phosphorus .sulfide-hydrocarbon product is preferably in excess of that required for formation of a normal barium salt of the said product, so that a basic salt is formed in this reaction. The amount of barium methylate employed should be sufficient to provide from about 4.5 parts, and preferably about 5 to 8 parts, of barium per part of phosphorus supplied by the phosphorus sulfide-hydrocarbon reaction product, the basic salt thus formed containing more than 4 and up to about 6 parts of barium per part of phosphorus. The formation of salts having ratios above this level requires carbonation of the basic barium salt and subsequent reaction of the carbonated salt with additional barium methylate.

The carbonation of the basic barium salt formed in the initial barium methylate reaction should be carried out to an extent suflicient to incorporate into the basic salt substantially one mol of carbon dioxide for each mol of basic barium (i.e., barium over and above that constituting neutral salt) present in 'the basic barium salt. Expressed on a Weight basis, this amounts to substantially 0.3 part of carbon dioxide per part of basic barium in the basic salt.

The amount of barium (as barium methylate) employed in any subsequent barium methylate treating step of the process can vary from a very small amount, say, about 0.25 to about 4.0 parts, by weight, preferably about 3 to 4 parts, per part of phosphorus supplied by the starting air-blown phosphorus sulfide-hydrocarbon reaction product. As aforesaid, additional carbonation and barium methylate treating steps may be employed to further raise the barium level of the product salts, each carbonation step being carried out to an extent sufficient to incorporate about 0.3 part, by weight, of carbon dioxide per part of barium incorporated by the preceding barium methylate reaction.

It should be pointed out that the barium methylate reagent may be supplied to the initial barium methylate reaction in two portions with water being added only in connection with the second portion. Thus, since the presence of water is not necessary for the formation of the normal salt of the air-blown phosphorus sulfide-hydrocarbon reaction product but only the basic salt, it need not be added with the first portion of barium methylate charge.

Although the present invention has been described herein by means of certain specific embodiments and illustrative examples, it is not intended that the scope thereof be limited in any way thereby, but only as indicated in the following claims.

What is claimed is:

1. A phosphorus sulfide-mono-olefinic hydrocarbon reaction product prepared by the steps of (1) reacting a polyolefin hydrocarbon polymer with from about 1% to about 50% by weight of a phosphorus sulfide in a nonoxidizing atmosphere to form a phosphorus sulfide-hydrocarbon reaction product, and (2) introducing into said reaction product a gas selected from the group consisting of oxygen and air at a temperature in the range of about to about 200 C.

2. A barium salt of a phosphosulfurized polyolefin prepared by the steps of (1) reacting a mono-olefinic hydrocarbon polymer having a molecular weight in the range of about 500 to about 50,000 with from about 1% to about 50% by weight of a phosphorus sulfide in a nonoxidizing atmosphere to form a phosphorus sulfide-hydrocarbon reaction product, (2) introducing air into said reaction product at a temperature in the range of about 100 to about 200 C., and (3) reacting the product of step (2) with barium methylate to form the barium salt of said product.

3. The process which comprises the steps of (1) reacting a mono-olefinic hydrocarbon polymer with from about 1% to about 50% by Weight of a phosphorus sulfide in a non-oxidizing atmosphere, to form a phosphorus sulfide-hydrocarbon reaction "product, (2) and introducing into said reaction product a gas selected from the group consisting of oxygen and air at a temperature in the range of about 100 to about 200 C.

4.'The process of claim 3 wherein the hydrocarbon polymer in step 1) is reacted with from about 5% to about 25% by weight of said phosphorus sulfide.

5. The process .of claim 3 wherein the gas is air.

6. The process of claim 5 wherein the air is introduced at a rate of 0.15 to 2.00 liters per minute per kilogram of said reaction product.

7. The process for preparing barium salts which comprises the steps of ,(1) reacting a mono-olefinic hydrocarbon polymer having a molecular weightin the range of about 500 to about 50,000 with from about 1% to about 50% by weight of a phosphorus sulfide in a nonoxidizing atmosphere, to form a phosphorus sulfide-hydrocarbon reaction product, (2) introducing into said reaction product a gas selected from the group consisting of oxygen and air at a temperature in the range of about 100 to .about 200 C., and (3') reacting the resulting product of step ,(2) with barium methylate, to form a barium salt of said product.

8. The process of claim 7 wherein the gas is introduced at a rate of about 0.15 to about 2.0 liters per minute per kilogram of the reaction product and for at least one hour, but insufficient to substantially alter the S:P ratio of the mono-olefinic hydrocarbon polymer.

9. The process of claim 7 wherein the mono-olefinic hydrocarbon polymer is polypropylene having a molecular weight in the range of about 500 to about 1500.

10. The process of claim 8 wherein the gas is air.

11. The process of preparing a barium salt which comprises the steps of (1) reacting polypropylene having a molecular Weight in'the range of about 500 to about 1500 with from about 5% to about 25 of phosphorus pentasulfide in .a nitrogen atmosphere to form a P S -polypropylene reaction product, (2) passing air into said reaction product at a temperature of about to about 200 C. for about one hour, and (3) reacting the product of step (2) with barium methylate to form the barium salt of said product.

12. The process of claim 11, wherein the gas is introduced at a rate of about 0.2 to 0.5 liter per minute perkilogram of said reaction product.

References Cited "by the Examiner UNITED STATES PATENTS 3/1963 Coonradt et al 260-139 CHAR-LES B. PARKER, Primary Examiner.

DANIEL D. HORVVITZ, Examiner. 

1. A PHOSPHORUS SULFIDE MONO-OLEFINIC HYDROCARBON REACTION PRODUCT PREPARED BY THE STEPS OF (1) REACTING A POLYOLEFIN HYDROCARBON POLYMER WITH FROM ABOUT 1% TO ABOUT 50% BY WEIGHT OF A PHOSPHORUS SULFIDE IN A NONOXIDIZING ATMOSPHERE TO FORM A PHOSPHORUS SULFIDE-HYDROCARBON REACTION PRODUCT, AND (2) INTRODUCING INTO SAID REACTION PRODUCT A GAS SELECTED FROM THE GROUP CONSISTING OF OXYGEN AND AIR AT A TEMPERATURE IN THE RANGE OF ABOUT 100* TO ABOUT 200*C.
 3. THE PROCESS WHICH COMPRISES THE STEPS OF (1) REACTING A MONO-OLEFINIC HYDROCARBON POLYMER WITH FROM ABOUT 1% TO ABOUT 50% BY WEIGHT OF A PHOSPHORUS SULFIDE IN A NON-OXIDIZING ATMOSPHERE, TO FORM A PHOSPHORUS SULFIDE-HYDROCARBON REACTION PRODUCE, (2) AND INTRODUCING INTO SAID REACTION PRODUCT A GAS SELECTED FROM THE GROUP CONSISTING OF OXYGEN AND AIR AT A TEMPERATURE IN THE RANGE OF ABOUT 100* TO ABOUT 200*C. 